It has been proposed to employ layered coding of audio and video transmitted in video conferencing and telephone conferencing systems. For example, U.S. Pat. No. 7,593,032, issued Sep. 22, 2009 to Civanlar, et al., discloses a video conferencing system in which transmitted audio and video are encoded using a layered coding scheme, and in which all or some of the layers of a full set of layers of the encoded video or audio may be transmitted.
It has also been proposed to encode audio data so that the encoded audio includes a monophonic layer and directional metadata which can be used (e.g., in a teleconferencing system) to render the monophonic audio content as an output soundfield (e.g., for playback on multiple loudspeakers). See, for example, V. Pulkki, et al., “Directional Audio Coding-Perception-based Reproduction of Spatial Sound,” in International Workshop on the Principles and Applications of Spatial Hearing, Nov. 11-13, 2009, Zao, Miyagi, Japan.
However, until the present invention, it had not been known how to select layers (e.g., a subset of a full set of layers) of a spatially layered, encoded audio signal, in a manner providing any of a variety of benefits (described hereinbelow), including provision of a perceptually continuous teleconferencing listening experience at endpoints of a teleconferencing system, or to select layers of a spatially layered, encoded audio signal so as to provide a mix of soundfield and monophonic layers which varies over time (e.g., in a continuous manner) to endpoints of a conferencing system during a teleconference. Nor had it been known to select layers of a spatially layered, encoded audio signal to provide a selection of layers which varies over time (e.g., in a continuous manner) during a teleconference in a manner determined by application of a predetermined set of rules, where the rules relate selected subsets of layers to analyzed characteristics of at least one endpoint of a conferencing system or of audio content captured or transmitted by at least one endpoint of a conferencing system.